Photochemical effects on microbial activity in natural waters: the interaction of reactive oxygen species and dissolved organic matter

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• 作者：Scully ; Norman M. ; Cooper ; William J. ; Tranvik ; Lars J.
• 关键词：Dissolved organic matter ; Bacterial growth ; Reactive oxygen species ; Photochemistry ; Lake ; Ultraviolet
• 刊名：FEMS Microbiology Ecology
• 出版年：2003
• 出版时间：December 5, 2003
• 年：2003
• 卷：46
• 期：3
• 页码：353-357
• 全文大小：218 K

文摘

Bacterial utilization of dissolved organic matter (DOM) in surface waters is closely linked to photochemical transformations of DOM. Photochemically produced reactive oxygen species (ROS) play a central role in many photochemical reactions, but the role of ROS for the photochemical facilitation of bacterial utilization of DOM is previously not known. We exposed lake water with high DOM concentrations to simulated sunlight, with and without the addition of ROS scavengers, and quantified the effect on the production of CO₂, the loss of DOM absorbance, and bacterial growth. The photodegradation of DOM through microbial–photochemical interactions was dependent on the action of ROS. The use of ROS scavengers in irradiations of the lake water revealed that photobleaching below 300 nm and the production of CO₂ are highly dependent on the action of ROS. Photobleaching and CO₂ production in irradiated waters decreased significantly with the addition of ROS scavengers, but post-irradiation bacterial growth in the samples containing an ROS scavenger increased significantly above those without. The decrease in ROS activity (CO₂ production) likely caused an accumulation of bioavailable DOM and enhanced microbial processes. Rapid degradation of DOM through the action of ROS would be especially important in high DOM systems. The high photochemical ROS activity may counterbalance the positive effects on bacterial activity of DOM photolysis into bioavailable molecules.